Frank Cottrell Boyce, bestselling author of Framed, explores the fascinating real-life history behind the story and adapting the book for television.

During World War II, Winston Churchill made the safety of the paintings in the National Gallery his personal responsibility. Art is often looted in wartime (that's how a lot of the paintings in the gallery got there in the first place), and he was determined that it wouldn't happen in London. The paintings were hidden in a vast cave, in a slate mine, a mile underground in the remote town of Blaenau Ffestiniog in North Wales. It was supposed to be top secret but a convoy of trucks must have been a fairly conspicuous event in the town. Especially as the railway bridge was too low to let them pass and they had to lower the road.

Once a month one of the paintings was sent back to London's National Gallery in Trafalgar Square and people would queue up just to look at one painting. 45,000 people came to look at Tintoretto's Noli Me Tangere. I've always found the thought of people risking the Blitz just to see a painting really moving. In fact in the Hermitage in St. Petersburg, the guides would still give tours of the gallery, even though the pictures had gone — pointing to empty spaces and describing the Michelangelos or Caravaggios that used to hang there.

I've always known about this story since for some reason my parents thought that this grey and rainy town with its mountainous piles of waste slate, was the ideal holiday location and we spent most summers there when I was a child. My son says it looks "like Mordor" from The Lord of the Rings.

For a long time I thought the contrast between the grey of the town and the color of the paintings would make a great visual story but I didn't want to write about WWII. Then I suddenly thought — why not say it all happened again? Why not tell the story in a contemporary setting. So I was off ... thinking about how or why art is — or can be — important. Especially when people are short of money.

I wrote really quickly. It seemed really obvious that you could have one story per monthly painting so it had a nice shape. The research was the most fun ever — just wandering around the National Gallery or the hills of Snowdonia in Wales, where people are so friendly. I even learned a bit of Welsh.

One day around Christmas, I went for a walk on the freezing cold beach near where I live. I climbed over the dunes to the promenade and saw an amazing thing beneath me — hundreds and hundreds of people were also going for walks but nearly all of them were holding umbrellas — a blaze of colors and patterns that stretched for a mile — a psychedelic boa constrictor as it says in the book. I put it straight into the book, alongside Renoir's Les Parapluies.

Nearly everyone chooses it as their favorite bit of the book. One local authority in Wales even used it to inspire a "walk to school" scheme. One of the happiest days of my life was spent wandering up and down the Conwy Valley watching crocodiles of umbrella toting primary school children walk to school, inspired by my book!

Sadly it was really hard to keep the scene in the book and in the end it went.

That's as good an illustration as any of the pain of adaptation. I really wanted to keep that scene but even I couldn't find a way to make it fit in with the film. The film just became a thing of its own — less about the little boy who narrates the book and more about the love story between the grown-ups. It's just very different. More romantic than the book but less umbrella-ish.

Framed has been an amazing journey for me. When the book first came out I spent a lot of time visiting schools in Snowdonia and reading my favorite bits to them and seeing the amazing art work — and cakes! — they made in response to the book.

Then to go back a few years later and shoot a film of the book there — with some of those same children as extras — was amazing. Watching my story come to life in the very place where I had first imagined it. It was as though I was dreaming the whole town. The film unit caused a huge amount of excitement in the town, just as the original paintings had.

The other big danger of adaptation of course is that you sometimes forget that some of the things you described in the book were totally made up. For instance, in the book, the little boy hero says that sheep will follow you anywhere if you just open a packet of potato chips. I completely forgot that I invented this detail. One day we spent a freezing cold morning up on top of the mountain as the weather flicked from rain to sun to hail to snow to sun again in rapid succession. A shepherd and his sheep dog had a dozen sheep penned up in a corner ready for their cue. The director shouted "Action!" The dog nosed the sheep towards the little boy actor. He opened his packet of crisps and every sheep ran MILES at an incredible speed. I think we emptied Snowdonia of sheep. Every single person on the set glared at me and said, "But you said ..."

Editor's note:Framed, premiering December 26th on Masterpiece on PBS, stars Trevor Eve (David Copperfield) and Eve Myles (Little Dorrit) in Frank Cottrell Boyce's television adaptation of his own best-selling novel, about an eccentric Welsh village who learns that London's National Gallery is storing its entire art collection in a nearby mine during the museums renovations — leading to curious encounters between the village locals and the gallery's urbane, lovelorn curator.

Frank Cottrell Boyce is the author of several well-known books for children including Framed, Cosmic and Millions, which was adapted into a film by director Danny Boyle. Boyce is also a successful screenwriter, whose credits include Hilary and Jackie, Welcome to Sarajevo and Masterpiece contemporary's God on Trial.

Funding for the series is provided by Viking River Cruises and Ralph Lauren Corporation, with additional support from public television viewers and contributors to The Masterpiece Trust, created to help ensure the series' future.